Dreaded locust swarms: Myths and facts

Tell me, what are the only good omens amid this bleak Covid-19 crisis? That nature is reviving itself. Dolphins have begun breaching our shores again, civets have started strolling through some Indian towns, rhinos have ventured into the streets of Nepal, and so on.

All have been good but one. Locusts have been swarming from East Africa, to the Arabian Peninsula to as close as Pakistan. The problem is ongoing. The monsoon season is knocking on the horizon and could proliferate the swarm manifold. It is worrying; yet, not to the extent of the possibility of it reaching here, Bangladesh.

So, when I came across a supposed locust-like menace in some orchards of Cox's Bazaar, given the facts I know, I was indifferent. Then, my compatriot Tanim Ashraf pointed to certain butterfly effects of this alleged news. Allegations instill rumours. Rumours lead to fears and fears to mass cleansing of wild ecosystems. A chain reaction sets in. As we know, to incur the highest toll, it is always about the collateral and the repercussions. Covid-19 is one such example.

I, eventually, feel compelled to share a narrative with you all. Is the locust the only demon to comprehend? Is it the underlying cause that we should fear most? Or, is it safer that we first understand the means of destroying them?

Hop on with me and have a good read!

What is a locust?

As simple as it may sound, "locust" is an aggregation or grouping. The type we are talking about is formed by a mere insect. That insect is a grasshopper. If you read this in your garden, be it on your balcony or rooftop, you might readily encounter one. If you do, do not rush for the aerosol. Not all hoppers are infamous.

There are certain types that can build great swarming clouds under certain conditions. In general, they are from a group best identified by their stout horn-like antennae. Often called the short-horned grasshopper, they are diminutive among the insects. However, their stature is compensated for by two unique features. They have many forms; each is dedicated to cope with exclusive habitat status. And, in winged morph, they grow two robust pairs; so robust that they are also called bird grasshoppers.

In science, these bird-winged, short-horned, polymorphic grasshoppers are placed in genera: Schistocerca, Locusta, Chortoicetes and Nomadacris.

The pillage

The destruction caused by locusts has been documented since time immemorial. The ancient Egyptians and the Chinese before the Common Era wrote about it. Locusts feature as a plague in the Holy Books. To date, the swarms are of concern globally.

How pervasive can a swarm be? The swarms are swift and agile. More notorious desert locust aggregation can be nearly 1,000 square kilometres in size. About one square kilometre of that living cloud can hold 80 million insects. In 1954, a swarm traversed Europe, from northwest Africa to Great Britain. In 1988, another made a lengthy trans-Atlantic flight.

Locusts have an insatiable appetite. This conflicts with our vital harvests of: maize, rice, wheat, barley, cotton, sugarcane, you name it. It is said that one square-kilometre-sized swarm devours an amount of food that would feed 35,000 people.

The reasoning

At this point, the why question has become obvious. Why does a peaceful insect about the size of a paper clip yield a large army? Why have they become the monger of famine and starvation for us? In the advent of time, we have decoded the puzzle. Take a world map, plot all locust attacks, ancient and contemporary. The dry, arid and semi-arid regions stay most in the crosshairs. Plus, where forests and grasses have been used for agriculture, locusts have started to arise!

Locust upsurges are directly related to some sequential environmental changes. Heavy downpours, after dry weather and droughts, spurt vegetative growth. Rain has become more erratic than ever, thanks to climate change we set in motion.

Locust-forming grasshoppers, normal otherwise, get a hormonal drive through abrupt precipitation. They start breeding rapidly; which requires energy, ultimately creating their proverbial hunger. Desert rims, tropical or temperate, thus, are the most susceptible. The years following the clearing of grass or forest patches are the time most prone to the appearance of swarms.

Scenario: Bangladesh

Before calculating the risk, we should first look at the historical trend. The Indian Subcontinent has seen three different species: the desert locust, the migratory locust and the region's very own Bombay locust. As per the Food and Agricultural Organization's "Locust Handbook," swarms have always formed in the semi-arid regions of India and Pakistan. The last all-India swarm of Bombay locusts formed in 1908. Surges by other locusts occurred in the sixties.

Eastward, attacks are observed as far as: Thailand, Vietnam, Laos, the Indonesian archipelago, and Australia. These are mostly caused by the regional species like the Australian plague locust – sequential with forest destruction.

Bangladesh is always a low-risk country for locust plagues. Rain and water never experience such highs and lows. Then again, climate change is making predictions harder.

To contain the mini-beasts

Weapons bring destruction. Insecticides are no different. Clouds of living hoppers will appear eerie, but, millions of dead, smashed and gooey insects are grimmer and grislier. The air heavy with the stench of insect spray will only complete a view of hell. So, we must act accordingly.

I watched with horror, as I believe many of you did, when the Cox's Bazar orchards were nuked with cypermethrin. Like many other synthetic killers, this is lethal to many beneficial insects including bees. Imagine a world without bees. There will indeed be a silent spring.

Before seeking short-term remedies, at first, we better know the infesting insect and identify it correctly. We better remember that wingless hoppers are easier to control. We better seek eco-friendly remedies: Pakistan is deploying domestic ducks; there are other insects and animals that eat locusts and pests. We better not destroy them altogether. We better think multiple times before destroying a wild habitat.

Finally, it is better for you, me and everyone to have a good understanding with nature. Our indifference and ignorance did let loose one monstrous virus. Let's not make things more complicated.

Eco-friendly pest control

Wasps

Wasps are the cousins of bees – more wicked and extremely good at pest-hunting. It is said that every known pest insect has one wasp killer exclusively adept at hunting it. Wasps do not hunt to eat, rather they do it to lay eggs on the ill-fated host. Wasps are specialised parasites who get their own term of practice – parasitoidy.

Light traps

Light attracts insects. It is easy in theory, even easier to deploy. With a combination of a glued or watery base, a single light trap, per night, can kill thousands of mostly harmful: caterpillars, moths, hoppers, and beetles. Light traps are effective in killing a broad range of potential pests.

Pheromone or sweet traps

This mechanism is like light traps. However, here, we deceive the insects with smell, targeting the male bugs. Insects are prolific breeders and communicate mostly via olfaction. These traps lure the males by emanating the smell of a female counterpart possessed with a breeding call. This sort of smell is species-or group-specific. This trap, thus, acts with efficiency to kill targeted nuisances.